My application involves a body worn tag, causing significant receive signal strength variations at the anchors depending on body position and location of the tag on the body. I understand there is a range bias correction for a TWR use case, but what about TDOA?
Any suggestions on how to correct timestamps for range bias/signal strength variations in a TDOA setup?
The signal strength Vs range bias curve should be the same for both modes of operation.
You may however need to halve the bias amounts in comparison to the TWR values since in a TWR application you get the same impact in each direction giving double the effect in total.
I use TDOA in an environment where there are too many objects for my signal strength to be reliable (however, still in line of sight operation).
The way I “solved it” was to determine the true range bias error (real distance vs. measured distance) for the units during two way ranging. Then, when ranging using TDOA I would calculate a position (without range bias) and figure out my tag-to-anchor pseudo ranges, apply the range bias, and calculate my position again (I found that one iteration worked well enough for my needs, but I’m sure there are cases when it won’t).
Unfortunately I’m not skilled enough to say if this is a solution that converges all the time, but based on my requirements and testing, it worked.